Add initial bitrate and frame resolution parameters to quality scaler.

webrtc/modules/video_coding/utility/quality_scaler.cc

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #include "webrtc/modules/video_coding/utility/quality_scaler.h"
@@ skipping 12 matching lines @@
 QualityScaler::QualityScaler()
     : num_samples_(0),
       low_qp_threshold_(-1),
       downscale_shift_(0),
       framerate_down_(false),
       min_width_(kDefaultMinDownscaleDimension),
       min_height_(kDefaultMinDownscaleDimension) {}
 
 void QualityScaler::Init(int low_qp_threshold,
                          int high_qp_threshold,
-                         bool use_framerate_reduction) {
+                         bool use_framerate_reduction,
+                         int initial_bitrate_kbps,
+                         int width,
+                         int height) {
   ClearSamples();
   low_qp_threshold_ = low_qp_threshold;
   high_qp_threshold_ = high_qp_threshold;
   use_framerate_reduction_ = use_framerate_reduction;
+  // TODO(glaznev): investigate using thresholds for other resolutions
+  // ot threshold tables.

[sprang, 2016/02/15 13:20:21]

s/investigate/Investigare s/ot/or
Could we name these constants in the meantime? Or derive from current ones
(kWidthVga * kHeightVga + 15% for instance).

[AlexG, 2016/02/16 22:26:34]

Done.

+  if (initial_bitrate_kbps > 0 && initial_bitrate_kbps < 500) {
+    // Start scaling to roughly VGA.
+    while (width * height > 700 * 500) {
+      ++downscale_shift_;
+      width /= 2;
+      height /= 2;
+    }
+  }
   target_framerate_ = -1;
 }
 
 void QualityScaler::SetMinResolution(int min_width, int min_height) {
   min_width_ = min_width;
   min_height_ = min_height;
 }
 
 // Report framerate(fps) to estimate # of samples.
 void QualityScaler::ReportFramerate(int framerate) {
@@ skipping 93 matching lines @@
 }
 
 void QualityScaler::AdjustScale(bool up) {
   downscale_shift_ += up ? -1 : 1;
   if (downscale_shift_ < 0)
     downscale_shift_ = 0;
   ClearSamples();
 }
 
 }  // namespace webrtc